GAD 4 FTS : Make final Feature Addition and fix notifications

[theoden42]

Issue that this pull request solves

1. Notifications on forward file and send from drafts were not working
2. Drafts saving made some unnecesary fields as required
3. File attachments did not allow ZIP files

Closes: # (issue number)

Proposed changes

1. Implement notifications from all kind of send and forward
2. Allow person to download a file as a ZIP object, containing all the attachments and the pdf version of the notesheet
3. Create file view now shows a warning if there are unsaved changes
4. File View tab now allows the user to see on what tab they are (UI Change)

Brief description of what is fixed or changed

The above fixes are implemented to finalize the working of FTS, also the features which were required have been added as needed, the UI changes are demonstrated using the screenshots and other backend changes are mostly in the views.py file.

Types of changes

Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (please describe):

Checklist

Put an x in the boxes that apply

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have created new branch for this pull request
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• My changes does not break the current system and it passes all the current test cases.

Screenshots

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Please attach the screenshots of the changes made in case of change in user interface

Other information

Any other information that is important to this pull request

[prajjwalkapoor]

Changes LGTM.